1. Field of the Invention
The invention relates to a vertically downward back-light module and, more particularly, to a back-light module that transfers light rays into a light plane, suitable for use with LCD devices.
2. Description of the Related Art
Traditionally, a display device uses electron beam technology to produce light and image on a curved or flat surface display screen. Due to the constraints of electron beam technology, this traditional display device usually requires the mount of a voluminous electron tube.
With the development of liquid crystal display (LCD) technology, the size and weight of the display device are substantially reduced, which not only improves the esthetic of the display device but also its carrying. The modern LCD device usually incorporates the mount of a back-light module that provides the adequate light to the flat display panel. An important factor then is the light uniformity provided by the back-light module at every position of the display screen.
As illustrated in FIG. 1, a conventional back-light module comprises a light-guiding panel 1a, a light source 2a, a reflective element 3a, and a base 4a. The light-guiding panel 1a includes a top light outgoing surface 10a and a bottom light entry surface 11a. The light source 2a is mounted below the light entry surface 11a at a corresponding central location. The reflective element 3a covers the lateral sides of the light-guiding panel 1a. The base 4a is formed arcuate, receiving the mount of the light-guiding panel 1a and the light source 2athereon. The light from the light source 2ais thereby outputted via the light outgoing surface 10a, and loss of light through other parts of the light-guiding panel 1a, except the light outgoing surface 10a, is thereby prevented. The reflective element 40a is formed on the surface of the base 4a by, for example, plating, to provide light reflection and increase the brightness of the light outgoing surface 10a. 
In the above back-light module, the light from the light outgoing surface is substantially concentrated around the light source at a central location below the light entry surface. The brightness of the light outgoing surface is therefore excessive at the central region and gradually decreases along the lateral sides. The light uniformity therefore is not satisfactory. Furthermore, due to the arcuate shape of the base, the size and more particularly the thickness of the back-light module are therefore relatively large, which increases the surface area of the reflective element and, consequently, the fabrication cost.
It is therefore a principal object of the invention to provide a vertically downward back-light module that improves the light uniformity and the brightness of the light outgoing surface of the light-guiding panel.
It is another object of the invention to provide a vertically downward back-light module that is dimensionally reduced to an adequate thinness.
To accomplish the above and other objectives, a vertically downward back-light module of the invention comprises a light-guiding panel, a light source, a reflective clement, and a base. The light-guiding panel includes a bottom reflecting surface in which is formed a slot having a corrugated diffusing surface and light entry side surfaces. The light-guiding panel includes lateral wings respectively extending at a side of each light entry side surface. Each lateral wing extends with an inclination angle relative to a horizontal plane including the opening of the slot through the bottom reflecting surface. The light source is placed in the slot. The reflective element covers the bottom reflecting surface and encapsulates the light source in the light-guiding panel. The light-guiding panel with the light source are mounted on the base.
To provide a further understanding of the invention, the following detailed description illustrates embodiments and examples of the invention, this detailed description being provided only for illustration of the invention.